The present invention relates, in general, to the field of magnetoresistive ("MR") and giant magnetoresistive ("GMR") read/write heads. More! particularly, the present invention relates to a technique for top surface imaging for top pole tip width control in MR write head processing.
Top pole tip definition for the write transducer portion of a read/write head and its critical dimension ("CD") control currently present major challenges in thin film MR/GMR head processing. As the demand for ever more storage capacity in disk drives intensifies resulting in the need for areal recording densities of on the order of 20,000 to 35,000 tracks per inch ("TPI") and greater, future generations of these heads must then exhibit a track width which is increasingly reduced while nevertheless maintaining a high stack height for performance reasons.
As a consequence, these constraints imply that the critical dimensions of the top pole tip of the write head must be in the sub-micron range of on the order of 0.30 to 0.8 microns (".mu.m"). However, utilizing current thin film photolithography techniques and steppers, it is extremely difficult to pattern tip widths of such narrow dimensions while also providing high aspect ratios and vertical profiles together with tight critical dimension control due to the limitation of resolution inherent in a conventional thick photoresist pattern of on the order of 6.0 .mu.m-10.0 .mu.m. While conventional processing can be used in conjunction with a slider level pole trim operation as one way to achieve a sub-micron write track width, such an operation is extremely costly in a manufacturing environment with the further possibility that it can easily result in damage to the associated MR and/or GMR read sensor.